The present invention relates to bicycle wheel hubs with power meters.
Cyclists are often looking for tools for training. For example, bicycles are often provided with sensors and processors for measuring speed, distance, and cadence (often called “bike computers”). In addition, pulse monitors can be used to provide the rider with real time data on the user's heart rate.
Recent improvements in electronics technology have resulted in the development of devices for measuring the power generated by the cyclist, often called “power meters.” There are different types of power meters, but most are based on the calculation of power based on torque multiplied by cadence. Torque can be measured in a variety of ways, such as by measuring force on the pedals multiplied by length of the crank arm, or force in the chain multiplied by radius of the chainring.
Some power meters are located in the hub of the rear wheel of the bicycle. Some of those hub-based power meters measure torque using a diagonal strain gage positioned on a torque tube positioned inside the rear hub. The torque tube transmits the torque from a rear cog to the hub shell. The measured torque can then be multiplied by the rpm of the rear wheel in order to determine power.